Over the next decade, roughly 150,000 low-income renters in California will see their apartment buildings outfitted with solar panels — and their electricity bills drop.

Regulations approved this week cleared the way for the state to spend $1 billion over 10 years — using proceeds from the state’s landmark climate-change program — on incentives for landlords to install rooftop solar panels on apartment buildings housing low-income residents.

“There’s been a lot of discussion about why we can’t get rooftop solar in the communities that need it most,” said Shana Lazero, legal director for the Richmond-based Communities for a Better Environment, which was part of a coalition that co-sponsored the solar legislation. “One of the hardest nuts to crack is the rental market. It’s a huge step to solving one of the biggest pieces of the problem.”

From costly solar panels to costlier Teslas, renewable energy is often associated with environmentally conscious elites — not poor families who live near factories and crowded freeways, suffering the most from the side-effects of a fossil fuel economy. In fact, a common criticism of California’s early climate-change approach was that the poor and working class were paying more to subsidize the electric vehicles and solar panels of the wealthy — “and there was some truth to that,” said Ethan Elkind, a UC Berkeley law professor who is director of the climate program for the school’s Center for Law, Energy & the Environment.

But in recent years, Elkind said, the state Legislature has tried to democratize its climate-change initiatives by investing more in those hit hardest by pollution.

“There are strong moral reasons to do that. There are strong economic reasons, too,” he said. “We want more people in California, particularly low-income people in disadvantaged communities, to feel a stake in the state’s climate programs and receive benefits from them.”

To qualify for the Solar on Multifamily Affordable Housing program, known as SOMAH, an apartment building must include at least five subsidized units for low-income tenants. It also must either be located in a disadvantaged area or be inhabited mostly by families earning 60 percent of the area’s typical income. Landlords will apply for the incentives.

By law, at least 51 percent of the utility savings must go back to the tenant — a key aspect of the program.

The timeline for the new solar program also provides a window into the speed of bureaucracy: The bill creating the program — carried by Assemblywoman Susan Eggman, D-Stockton — was signed into law in 2015. Since then, it has undergone a halting regulatory process at the Public Utilities Commission, which this week approved the final regulations.

Lazero said she hoped that the first panels would be installed in the fall of 2018.

Co-sponsoring Eggman’s bill was the California Solar Energy Industries Association, which notes the challenge of installing solar panels on any multi-unit apartment building is far greater than on a single-family home, especially for a building housing low-income tenants.

But there is good news: As they become more common, solar panels have steadily gotten cheaper to install, said Kelly Knutsen, a senior policy adviser for the association. The cost per watt — $4.10 in 2015 — was $11.20 in 2000, according to data by the trade group.